[ios] - C++17 → C++20

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tmp/tmp_b9rt290/{from.md → to.md} +52 -54

tmp/tmp_b9rt290/{from.md → to.md} RENAMED Viewed

@@ -61,28 +61,27 @@ namespace std {
   };
 }
 ```
-#### `basic_ios` constructors <a id="basic.ios.cons">[[basic.ios.cons]]</a>
 ``` cpp
 explicit basic_ios(basic_streambuf<charT, traits>* sb);
 ```
-*Effects:* Constructs an object of class `basic_ios`, assigning initial
-values to its member objects by calling `init(sb)`.
 ``` cpp
 basic_ios();
 ```
-*Effects:* Constructs an object of class
-`basic_ios` ([[ios.base.cons]]) leaving its member objects
-uninitialized. The object shall be initialized by calling
-`basic_ios::init` before its first use or before it is destroyed,
-whichever comes first; otherwise the behavior is undefined.
 ``` cpp
 ~basic_ios();
 ```
@@ -90,14 +89,14 @@ whichever comes first; otherwise the behavior is undefined.
 ``` cpp
 void init(basic_streambuf<charT, traits>* sb);
 ```
-*Postconditions:* The postconditions of this function are indicated in
-Table  [[tab:iostreams.basicios.init.effects]].
-**Table: `basic_ios::init()` effects** <a id="tab:iostreams.basicios.init.effects">[tab:iostreams.basicios.init.effects]</a>
 | Element        | Value                                                        |
 | -------------- | ------------------------------------------------------------ |
 | `rdbuf()`      | `sb`                                                         |
 | `tie()`        | `0`                                                          |
@@ -123,15 +122,15 @@ sequence controlled by the stream buffer.
 ``` cpp
 basic_ostream<charT, traits>* tie(basic_ostream<charT, traits>* tiestr);
 ```
-*Requires:* If `tiestr` is not null, `tiestr` must not be reachable by
 traversing the linked list of tied stream objects starting from
 `tiestr->tie()`.
-*Postconditions:* `tiestr == tie()`.
 *Returns:* The previous value of `tie()`.
 ``` cpp
 basic_streambuf<charT, traits>* rdbuf() const;
@@ -141,22 +140,22 @@ basic_streambuf<charT, traits>* rdbuf() const;
 ``` cpp
 basic_streambuf<charT, traits>* rdbuf(basic_streambuf<charT, traits>* sb);
 ```
-*Postconditions:* `sb == rdbuf()`.
 *Effects:* Calls `clear()`.
 *Returns:* The previous value of `rdbuf()`.
 ``` cpp
 locale imbue(const locale& loc);
 ```
-*Effects:* Calls `ios_base::imbue(loc)` ([[ios.base.locales]]) and if
-`rdbuf() != 0` then `rdbuf()->pubimbue(loc)` ([[streambuf.locales]]).
 *Returns:* The prior value of `ios_base::imbue()`.
 ``` cpp
 char narrow(char_type c, char dfault) const;
@@ -179,45 +178,45 @@ specified field width.
 ``` cpp
 char_type fill(char_type fillch);
 ```
-*Postconditions:* `traits::eq(fillch, fill())`.
 *Returns:* The previous value of `fill()`.
 ``` cpp
 basic_ios& copyfmt(const basic_ios& rhs);
 ```
-*Effects:* If `(this == &rhs)` does nothing. Otherwise assigns to the
-member objects of `*this` the corresponding member objects of `rhs` as
-follows:
-1.  calls each registered callback pair `(fn, index)` as
- `(*fn)(erase_event, *this, index)`;
-2.  assigns to the member objects of `*this` the corresponding member
- objects of `rhs`, except that
   - `rdstate()`, `rdbuf()`, and `exceptions()` are left unchanged;
- - the contents of arrays pointed at by `pword` and `iword` are
-      copied, not the pointers themselves;[^10] and
   - if any newly stored pointer values in `*this` point at objects
- stored outside the object `rhs` and those objects are destroyed
-      when `rhs` is destroyed, the newly stored pointer values are
-      altered to point at newly constructed copies of the objects;
-3.  calls each callback pair that was copied from `rhs` as
- `(*fn)(copyfmt_event, *this, index)`;
-4.  calls `exceptions(rhs.exceptions())`.
 [*Note 1*: The second pass through the callback pairs permits a copied
 `pword` value to be zeroed, or to have its referent deep copied or
 reference counted, or to have other special action taken. — *end note*]
-*Postconditions:* The postconditions of this function are indicated in
-Table  [[tab:iostreams.copyfmt.effects]].
-**Table: `basic_ios::copyfmt()` effects** <a id="tab:iostreams.copyfmt.effects">[tab:iostreams.copyfmt.effects]</a>
 | Element        | Value              |
 | -------------- | ------------------ |
 | `rdbuf()`      | unchanged          |
 | `tie()`        | `rhs.tie()`        |
@@ -235,39 +234,38 @@ Table  [[tab:iostreams.copyfmt.effects]].
 ``` cpp
 void move(basic_ios& rhs);
 void move(basic_ios&& rhs);
 ```
-*Postconditions:* `*this` shall have the state that `rhs` had before the
-function call, except that `rdbuf()` shall return 0. `rhs` shall be in a
-valid but unspecified state, except that `rhs.rdbuf()` shall return the
-same value as it returned before the function call, and `rhs.tie()`
-shall return 0.
 ``` cpp
 void swap(basic_ios& rhs) noexcept;
 ```
-*Effects:* The states of `*this` and `rhs` shall be exchanged, except
-that `rdbuf()` shall return the same value as it returned before the
-function call, and `rhs.rdbuf()` shall return the same value as it
-returned before the function call.
 ``` cpp
 void set_rdbuf(basic_streambuf<charT, traits>* sb);
 ```
-*Requires:* `sb != nullptr`.
 *Effects:* Associates the `basic_streambuf` object pointed to by `sb`
 with this stream without calling `clear()`.
-*Postconditions:* `rdbuf() == sb`.
 *Throws:* Nothing.
-#### `basic_ios` flags functions <a id="iostate.flags">[[iostate.flags]]</a>
 ``` cpp
 explicit operator bool() const;
 ```
@@ -287,25 +285,25 @@ iostate rdstate() const;
 ``` cpp
 void clear(iostate state = goodbit);
 ```
-*Postconditions:* If `rdbuf() != 0` then `state == rdstate()`; otherwise
 `rdstate() == (state | ios_base::badbit)`.
 *Effects:* If
 `((state | (rdbuf() ? goodbit : badbit)) & exceptions()) == 0`, returns.
-Otherwise, the function throws an object of class
-`basic_ios::failure` ([[ios::failure]]), constructed with
-*implementation-defined* argument values.
 ``` cpp
 void setstate(iostate state);
 ```
 *Effects:* Calls `clear(rdstate() | state)` (which may throw
-`basic_ios::failure` ([[ios::failure]])).
 ``` cpp
 bool good() const;
 ```
@@ -338,9 +336,9 @@ exceptions to be thrown.
 ``` cpp
 void exceptions(iostate except);
 ```
-*Postconditions:* `except == exceptions()`.
 *Effects:* Calls `clear(rdstate())`.

   };
 }
 ```
+#### Constructors <a id="basic.ios.cons">[[basic.ios.cons]]</a>
 ``` cpp
 explicit basic_ios(basic_streambuf<charT, traits>* sb);
 ```
+*Effects:* Assigns initial values to its member objects by calling
+`init(sb)`.
 ``` cpp
 basic_ios();
 ```
+*Effects:* Leaves its member objects uninitialized. The object shall be
+initialized by calling `basic_ios::init` before its first use or before
+it is destroyed, whichever comes first; otherwise the behavior is
+undefined.
 ``` cpp
 ~basic_ios();
 ```
 ``` cpp
 void init(basic_streambuf<charT, traits>* sb);
 ```
+*Ensures:* The postconditions of this function are indicated in
+[[basic.ios.cons]].
+**Table: `basic_ios::init()` effects** <a id="basic.ios.cons">[basic.ios.cons]</a>
 | Element        | Value                                                        |
 | -------------- | ------------------------------------------------------------ |
 | `rdbuf()`      | `sb`                                                         |
 | `tie()`        | `0`                                                          |
 ``` cpp
 basic_ostream<charT, traits>* tie(basic_ostream<charT, traits>* tiestr);
 ```
+*Preconditions:* If `tiestr` is not null, `tiestr` is not reachable by
 traversing the linked list of tied stream objects starting from
 `tiestr->tie()`.
+*Ensures:* `tiestr == tie()`.
 *Returns:* The previous value of `tie()`.
 ``` cpp
 basic_streambuf<charT, traits>* rdbuf() const;
 ``` cpp
 basic_streambuf<charT, traits>* rdbuf(basic_streambuf<charT, traits>* sb);
 ```
 *Effects:* Calls `clear()`.
+*Ensures:* `sb == rdbuf()`.
 *Returns:* The previous value of `rdbuf()`.
 ``` cpp
 locale imbue(const locale& loc);
 ```
+*Effects:* Calls `ios_base::imbue(loc)` [[ios.base.locales]] and if
+`rdbuf() != 0` then `rdbuf()->pubimbue(loc)` [[streambuf.locales]].
 *Returns:* The prior value of `ios_base::imbue()`.
 ``` cpp
 char narrow(char_type c, char dfault) const;
 ``` cpp
 char_type fill(char_type fillch);
 ```
+*Ensures:* `traits::eq(fillch, fill())`.
 *Returns:* The previous value of `fill()`.
 ``` cpp
 basic_ios& copyfmt(const basic_ios& rhs);
 ```
+*Effects:* If `(this == addressof(rhs))` is `true` does nothing.
+Otherwise assigns to the member objects of `*this` the corresponding
+member objects of `rhs` as follows:
+- calls each registered callback pair `(fn, idx)` as
+ `(*fn)(erase_event, *this, idx)`;
+- then, assigns to the member objects of `*this` the corresponding
+  member objects of `rhs`, except that
   - `rdstate()`, `rdbuf()`, and `exceptions()` are left unchanged;
+ - the contents of arrays pointed at by `pword` and `iword` are copied,
+ not the pointers themselves;[^10] and
   - if any newly stored pointer values in `*this` point at objects
+ stored outside the object `rhs` and those objects are destroyed when
+ `rhs` is destroyed, the newly stored pointer values are altered to
+ point at newly constructed copies of the objects;
+- then, calls each callback pair that was copied from `rhs` as
+ `(*fn)(copyfmt_event, *this, idx)`;
+- then, calls `exceptions(rhs.exceptions())`.
 [*Note 1*: The second pass through the callback pairs permits a copied
 `pword` value to be zeroed, or to have its referent deep copied or
 reference counted, or to have other special action taken. — *end note*]
+*Ensures:* The postconditions of this function are indicated in
+[[basic.ios.copyfmt]].
+**Table: `basic_ios::copyfmt()` effects** <a id="basic.ios.copyfmt">[basic.ios.copyfmt]</a>
 | Element        | Value              |
 | -------------- | ------------------ |
 | `rdbuf()`      | unchanged          |
 | `tie()`        | `rhs.tie()`        |
 ``` cpp
 void move(basic_ios& rhs);
 void move(basic_ios&& rhs);
 ```
+*Ensures:* `*this` has the state that `rhs` had before the function
+call, except that `rdbuf()` returns `nullptr`. `rhs` is in a valid but
+unspecified state, except that `rhs.rdbuf()` returns the same value as
+it returned before the function call, and `rhs.tie()` returns `nullptr`.
 ``` cpp
 void swap(basic_ios& rhs) noexcept;
 ```
+*Effects:* The states of `*this` and `rhs` are exchanged, except that
+`rdbuf()` returns the same value as it returned before the function
+call, and `rhs.rdbuf()` returns the same value as it returned before the
+function call.
 ``` cpp
 void set_rdbuf(basic_streambuf<charT, traits>* sb);
 ```
+*Preconditions:* `sb != nullptr` is `true`.
 *Effects:* Associates the `basic_streambuf` object pointed to by `sb`
 with this stream without calling `clear()`.
+*Ensures:* `rdbuf() == sb` is `true`.
 *Throws:* Nothing.
+#### Flags functions <a id="iostate.flags">[[iostate.flags]]</a>
 ``` cpp
 explicit operator bool() const;
 ```
 ``` cpp
 void clear(iostate state = goodbit);
 ```
+*Ensures:* If `rdbuf() != 0` then `state == rdstate()`; otherwise
 `rdstate() == (state | ios_base::badbit)`.
 *Effects:* If
 `((state | (rdbuf() ? goodbit : badbit)) & exceptions()) == 0`, returns.
+Otherwise, the function throws an object of class `ios_base::failure`
+[[ios.failure]], constructed with *implementation-defined* argument
+values.
 ``` cpp
 void setstate(iostate state);
 ```
 *Effects:* Calls `clear(rdstate() | state)` (which may throw
+`ios_base::failure` [[ios.failure]]).
 ``` cpp
 bool good() const;
 ```
 ``` cpp
 void exceptions(iostate except);
 ```
+*Ensures:* `except == exceptions()`.
 *Effects:* Calls `clear(rdstate())`.

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